On Sat, 26 Nov 2011, Gabor Ruzsa wrote: Although I can't think of any reference right now, nor improvise a proof of inconsistency, my gut feeling is that you're absolutely right. However, restricting a software package to do only the "right" things would be a very bad idea. First, because what it considered "right" changes in time (and besides, who says what's right and what's wrong? --- but I digress). Second, because sometimes you _want_ to do wrong things on purpose, either for pedagogical purposes or just for fun. Third, because in certain cases you want to replicate other people's results, even when they do wrong things. So, gretl leaves you the option of being naughty or nice. Riccardo (Jack) Lucchetti Dipartimento di Economia Università Politecnica delle Marche r.lucchetti(a)univpm.it http://www.econ.univpm.it/lucchetti